package Class.Method.Recursion;

/**
 * Enjoy programming!!!
 * Time: 2021/11/6 -  20:27
 */
public class Peach {
    public static void main(String[] args){
        if (Tool1.back(-1) != -1)
        System.out.println(Tool1.back(-1));
    }
}
class Tool1{
    public static int back(int n){
        if (10 == n){
            return 1;
        }
        else if (n <= 9 && n >= 1){
            return 2 * (back(n + 1) + 1);
        }
        else{
            System.out.println("day在1-10之间");
            return -1;
        }
    }
}